TY - JOUR
T1 - An estimate of the equilibrium speciation of sulfur vapor over solid sulfur and implications for planetary atmospheres
AU - Lyons, James R.
N1 - Funding Information:
The author thanks K. Zahnle and an anonymous referee for helpful reviews, and gratefully acknowledges support from the UCLA IGPP Center for Astrobiology and the NASA Astrobiology Institute, and from the NASA Exobiology and Evolutionary Biology Program (Grant No. NNX07AK63G).
PY - 2008/6
Y1 - 2008/6
N2 - Sulfur allotropes have been observed in planetary atmospheres and are believed to have been present in the ancient Earth atmosphere. The vapor pressures of sulfur allotropes, especially S2, S3, and S4, are poorly known at typical atmospheric temperatures, but have generally been assumed to be high enough to represent significant gas phase abundances in model calculations. Here I present estimates of the speciation of the equilibrium vapor pressure over solid sulfur, which would seem to imply that the vapor pressures of most allotropes are too low at typical atmospheric temperatures for gas phase formation reactions to be important. However, consideration of the kinetics of condensation shows that gas phase sulfur allotrope reactions can be important under certain conditions. The implications for the mechanism of sulfur isotope mass-independent fractionation on early Earth are discussed. Implications for the presence of sulfur allotropes in Venusian clouds, the distribution of S2 in the atmosphere of Jupiter following the comet Shoemaker-Levy 9 impacts, and the observation of S2 in volcanic plumes on Io are also presented.
AB - Sulfur allotropes have been observed in planetary atmospheres and are believed to have been present in the ancient Earth atmosphere. The vapor pressures of sulfur allotropes, especially S2, S3, and S4, are poorly known at typical atmospheric temperatures, but have generally been assumed to be high enough to represent significant gas phase abundances in model calculations. Here I present estimates of the speciation of the equilibrium vapor pressure over solid sulfur, which would seem to imply that the vapor pressures of most allotropes are too low at typical atmospheric temperatures for gas phase formation reactions to be important. However, consideration of the kinetics of condensation shows that gas phase sulfur allotrope reactions can be important under certain conditions. The implications for the mechanism of sulfur isotope mass-independent fractionation on early Earth are discussed. Implications for the presence of sulfur allotropes in Venusian clouds, the distribution of S2 in the atmosphere of Jupiter following the comet Shoemaker-Levy 9 impacts, and the observation of S2 in volcanic plumes on Io are also presented.
KW - Atmospheric chemistry
KW - Mass-independent fractionation
KW - Planetary atmospheres
KW - Sulfur allotropes
KW - Vapor pressure
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U2 - 10.1080/17415990802195615
DO - 10.1080/17415990802195615
M3 - Article
AN - SCOPUS:45849120641
SN - 1741-5993
VL - 29
SP - 269
EP - 279
JO - Journal of Sulfur Chemistry
JF - Journal of Sulfur Chemistry
IS - 3-4
ER -